Ratchet wrenches having a mechanism for changing the direction of torque have been well known in the art for many years. Additionally, combination wrenches employing conventional ratcheting capability as well as a rotary movement of the socket shank that is independent of an oscillation of the handle have also been disclosed. The rotary movement, or as also referred to as a free-spinning mode, is used to either pre-tighten a nut or bolt until it becomes finger tight or to remove a nut or bolt after it has been broken loose by the ratchet section of the wrench.
Many of the patents disclosing wrenches with independent rotary motion describe complex mechanical designs requiring that a plurality of rotary drive elements, including the ratchet gear, be operated to produce the required free-spinning mode. Because of this mechanical complexity, the rotary drive may cause the wrench to bind or it may disengage under load from the drive mechanism causing a work stoppage and/or require a wrench repair. Additionally, the wrench wear-out rate is higher and it is more expensive to manufacture and maintain.
In some of these designs, it is also necessary that the handle rotate during a ratcheting operation. This condition makes it difficult to maintain a tight grip on the handle or if it is tightly gripped, an injury to the palm of the hand may result due to the abrasive action of the rotating handle. Additionally, the back pressure exerted on the two mating bevel gears, when the handle is firmly held during a ratcheting operation, causes accelerated wear on the gears.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention. However, the following U.S. patents are considered related and indicative of the state-of-the-art:
______________________________________ U.S. PAT. NO. INVENTOR ISSUED ______________________________________ 4,448,095 Blodgett, R. 15 May 1984 4,318,314 Furedi, E., et al 9 March 1982 4,277,989 Tracy, K. 14 July 1981 4,128,025 Main, H. 5 December 1978 4,086,829 Hudgins, J. 2 May 1978 3,733,936 Flynn, W. 22 May 1973 ______________________________________
The Blodgett patent discloses a ratchet wrench having a ratcheting mechanism that may be reversed by turning the handle of the wrench. The initial twist of the handle causes the driving elements ot ratchet in one direction. Continued turning of the handle, beyond the initial position, results in placing the wrench in the opposite ratcheting direction. The mechanism disclosed also allows the handle to remain stationery (not rotate) during a ratcheting stroke.
The Furedi patent discloses a ratchet wrench assembly that is used to unthread or thread a loosened nut or bolt from a threaded shaft. The wrench is comprised of a barrel assembly that includes a clutching mechanism that is connected to the drive shaft. Thus, rotation of the barrel assembly causes the drive shaft to rotate which, in turn, causes the drive stud to subsequently rotate in a responsive rotational direction.
The Tracy patent discloses a reversible ratchet wrench handle in which the actuator for the direction reversing mechanism is located close to the handle that is grasped by the user. This location permits the user to operate the actuator with the thumb of the hand holding the handle. Thus, changing the direction of operation of the wrench is a one handed rather than a two handed operation.
The Main patent discloses a ratchet wrench incorporating a ratcheting mechanism that includes a rotatable and extendable shaft housed within the wrench handle, a set of shaft mounted bevel gears, a circular bevel gear that drives the drive stud and a ratchet pawl switch.
When it is desired to use the wrench in the ratchet mode the shaft is fully inserted into the handle. In this position, one of the shaft bevel gears engages the gear on the ratched pawl allowing the wrench to ratchet in one direction. To ratchet in the opposite direction the shaft is rotated. When it is desired to operate the wrench in a non-ratchet mode to continue loosening a nut or bolt, the shaft is fully withdrawn from the handle. In this position, the bevel gear engaging the pawl is disconnected and instead the other shaft bevel gear directly engages the circular bevel gear.
The Hudgins patent discloses a ratchet wrench having a rotational hand-grip speed-handle located around the wrench handle. A drive means is included within the handle that connects the hand-grip to the ratchet means located in the wrench head. The rotation of a nut or bolt is achieved by rotating the speed-handle about its own axis. This feature may be used for final tightening or after the nut or bolt has been broken loose and is being unthreaded for removal. Thus, the wrench may be used in a conventional manner for exerting maximum torque force or used in a screw-driver fashion when only minimum force is required.
The Flynn patent discloses a wrench having both a ratchet drive and a high speed gear drive that is connected to and activated by a rotational hand-grip. To apply a nut to a stud, the nut is initially placed in the socket attached to the shank. The hand-grip is then rotated which transmits the rotational movement of the hand-grip to the nut via a shaft, gears and the socket shank. When the nut is relatively tight, the force of hand hand-grip is released and the wrench handle is oscillated back and forth to effect a normal ratchet operation. To remove a nut, the above steps are reversed, the ratchet being used to loosen the nut until it turns freely and then the hand-grip is rotated to finish removing the nut.
For background purposes and as indicative of the art to which the invention relates, references may be made to U.S. patent numbers:
______________________________________ U.S. PAT. NO. INVENTOR ISSUED ______________________________________ 4,311,072 Hudgins, J. 19 January 1982 4,137,801 Imperio, C. 6 February 1979 3,707,893 Hofman, B. 2 January 1973 ______________________________________